Method for hydroformylation, xanthene-bridged ligands and catalyst comprising a complex of said ligands

ABSTRACT

In a process for the hydroformylation of ethylenically unsaturated compounds, at least one complex of a metal of transition group VIII. with at least one phosphorus-, arsenic- or antimony-containing compound as ligand is used as hydroformylation catalyst, where the compound used as ligand in each case comprises two groups which comprise a P, As or Sb atom and at least two further hetero atoms and are bound to a xanthene-like molecular framework. New compounds of this type and catalysts which comprise at least one complex of a metal of transition group VIII. with at least one such compound as ligand are also provided.

[0001] The present invention relates to a process for thehydroformylation of ethylenically unsaturated compounds, in which atleast one complex of a metal of transition group VIII with at least onephosphorus-, arsenic- or antimony-containing compound as ligand is usedas hydroformylation catalyst, where the compound used as ligand in eachcase comprises at least two groups which comprise a P, As or Sb atom andat least two further hetero atoms and are bound to a xanthene-likemolecular framework. The invention also provides new compounds of thistype and catalysts which comprise at least one complex of a metal oftransition group VIII with at least one such compound as ligand.

[0002] Hydroformylation or the oxo process is an important industrialprocess and is employed for preparing aldehydes from olefins, carbonmonoxide and hydrogen. If desired, these aldehydes can be hydrogenatedby means of hydrogen in the same process step to give the correspondingoxo alcohols. The reaction itself is strongly exothermic and generallyproceeds under superatmospheric pressure and at elevated temperatures inthe presence of catalysts. Catalysts used are Co, Rh, Ir, Ru, Pd or Ptcompounds or complexes which may be modified with N- or P-containingligands to influence the activity and/or selectivity. Thehydroformylation reaction results in formation of mixtures of isomericaldehydes because of the possible CO addition on to each of the twocarbon atoms of a double bond. In addition, double bond isomerization,i.e. shifting of internal double bonds to a terminal position and viceversa, can also occur.

[0003] Owing to the substantially greater industrial importance ofα-aldehydes, optimization of the hydroformylation catalysts to achieve avery high hydroformylation activity together with a very low tendency toform double bonds not in the α position is sought. In addition, there isa need for hydroformylation catalysts which lead to good yields ofα-aldehydes and in particular n-aldehydes even when internal linearolefins are used as starting materials. Here, the catalyst must makepossible both the establishment of equilibrium between internal andterminal double bond isomers and the very selective hydroformylation ofthe terminal olefins.

[0004] The use of phosphorus-containing ligands for stabilizing and/oractivating the catalyst metal in rhodium-catalyzed low-pressurehydroformylation is known. Suitable phosphorus-containing ligands are,for example, phosphines, phosphinites, phosphonites, phosphites,phosphoramidites, phospholes and phosphabenzenes. The most widespreadligands at present are triarylphosphines such as triphenylphosphine andsulfonated triphenylphosphine, since these have sufficient stabilityunder the reaction conditions. However, a disadvantage of these ligandsis that, in general, only very high ligand excesses give satisfactoryyields, in particular of linear aldehydes.

[0005] In Angew. Chem. Int. Ed. 39, 1639 (2000), D. Selent et al.describe the isomerizing hydroformylation of internal olefins in thepresence of rhodium catalysts, with oxy-functionalized bisphenylmonophosphonites being used as ligands. A disadvantage of thesecatalysts is their low n-selectivity. Thus, in the hydroformylation ofisomeric n-octenes, n-nonanal is obtained in a yield of at most 47.9%.

[0006] WO-A-98/43935 describes the use of chelating ligands in catalystsfor hydroformylation.

[0007] In Tetrahedron Letters, Volume 34, No. 13, pages 2107 ff. (1993),in Tetrahedron Letters, Volume 36, No. 1, pages 75 ff. (1995) and inChem. Ber. 124, page 1705 ff. (1991), Haenel et al. describe thesynthesis of bis(diphenylphosphino)chelates having anthracene,dibenzofuran, dibenzothiophene and xanthene skeletons. The use of thesecompounds as catalysts is not described.

[0008] In J. Chem. Soc., Dalton Trans., 1998, pp. 2981-2988, W. Goertzet al. describe the use of chelating phosphines and phosphonites havinga thioxanthene skeleton for the nickel-catalyzed hydrocyanation ofstyrene. Use in hydroformylation is not described.

[0009] In Organometallics 1995, 14, pages 3081 to 3089, M. Kranenburg etal. describe chelating phosphines having a xanthene skeleton and theiruse for regioselective rhodium-catalyzed hydroformylation. Chelatingphosphonites and phosphites are not described in this document. Adisadvantage of these chelating phosphines is that they are not suitablefor the isomerizing hydroformylation of internal olefins with high α- orn-selectivity.

[0010] In Organometallics 1999, 18, pages 4765 to 4777, van der Veen etal. describe the use of phosphacyclic diphosphines having a xantheneskeleton as ligands for rhodium-catalyzed hydroformylation. Adisadvantage of these catalysts is their very low activity which makestheir use in industrial processes uneconomical.

[0011] WO 95/30680 describes bidentate phosphine ligands in which thephosphorus atoms may be bound to a xanthene skeleton and the use ofthese ligands in catalysts for hydroformylation. A disadvantage of thesecatalysts is that they are not suitable for the isomerizinghydroformylation of internal olefins with good α- or n-selectivity.

[0012] EP-A-0982314 describes bidentate carbocyclic or heterocyclicphosphine ligands and a process for preparing linear aldehydes byhydroformylation of internal olefins using such ligands. A disadvantageof these ligands is their very low activity which makes use inindustrial processes uneconomical.

[0013] DE-A-19827232 describes catalysts based on monodentate, bidentateor polydentate phosphinite ligands in which the phosphorus atom and theoxygen atom of the phosphinite group are part of a 5- to 8-memberedheterocycle, and their use in hydroformylation and hydrocyanation. Thebidentate ligands may have a xanthene skeleton. A disadvantage of theseligands is that they are in need of improvement in terms of the α- orn-selectivity in the isomerizing hydroformylation of internal olefins.

[0014] None of the abovementioned documents describes the use ofchelating phosphonites and phosphites having a xanthene skeleton asligands in catalysts for hydroformylation.

[0015] It is an object of the present invention to provide an improvedprocess for the hydroformylation of compounds containing at least oneethylenically unsaturated double bond. Here, a very high proportion ofα-aldehydes or α-alcohols should preferably be obtained in thehydroformylation of α-olefins. In particular, the process should besuitable for the hydroformylation of internal linear olefins with highregioselectivity in favor of terminal product aldehydes. A furtherobject of the invention is to provide new compounds and novel catalystscomprising at least one complex of a metal of transition group VIII withsuch a compound as ligand.

[0016] We have found that these objects are achieved by ahydroformylation process in which at least one complex of a metal oftransition group VIII with at least one phosphorus-, arsenic-and/orantimony-containing compound as ligand is used as hydroformylationcatalyst. This compound comprises two groups comprising a P, As and/orSb atom, with the P, As and Sb atoms being bound directly to at leasttwo further hetero atoms and with each of the two groups being bound toa different phenyl ring of a xanthene skeleton. The group is bounddirectly to the phenyl ring via the phosphorus, arsenic or antimony atomor via a hetero atom bound thereto.

[0017] The present invention accordingly provides a process for thehydroformylation of compounds containing at least one ethylenicallyunsaturated double bond by reaction with carbon monoxide and hydrogen inthe presence of a hydroformylation catalyst comprising at least onecomplex of a metal of transition group VIII with at least one ligandselected from among compounds of the general formula I

[0018] where

[0019] A¹ and A² are each, independently of one another, O, S,SiR^(a)R^(b), NR^(c) or CR⁵R⁶, where

[0020] R^(a), R^(b), R^(c), R⁵ and R⁶ are each, independently of oneanother, hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl,

[0021] Y¹ and y² are each, independently of one another, radicalscontaining at least one phosphorus, arsenic or antimony atom, where ineach case at least two substituted or unsubstituted hetero atomsselected from among O, S and NR^(c), where R^(c) is hydrogen, alkyl,cycloalkyl or aryl, are directly bound to the phosphorus, arsenic orantimony atom, and

[0022] R¹, R², R³ and R⁴ are each, independently of one another,hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl, hetaryl, COOR^(d),COO⁻M⁺, SO₃R^(d), SO⁻ ₃M⁺, NE¹E², NE¹E²E³⁺X⁻, alkylene-NE¹E²E³⁺X⁻,OR^(d), SR^(d), (CHR^(e)CH₂O)_(x)R^(d), (CH₂N(E¹))_(x)R^(d),(CH₂CH₂N(E¹))_(x)R^(d), halogen, trifluoromethyl, nitro, acyl or cyano,

[0023]  where

[0024] R^(d), E¹, E² and E³ are identical or different radicals selectedfrom among hydrogen, alkyl, cycloalkyl and aryl,

[0025] R^(e) is hydrogen, methyl or ethyl,

[0026] M⁺is a cation,

[0027] X⁻ is an anion, and

[0028] x is an integer from 1 to 120, or

[0029] R¹ and/or R³ together with two adjacent carbon atoms of thebenzene ring to which they are bound form a fused ring system having 1,2 or 3 further rings.

[0030] For the purposes of the present invention, the expression ‘alkyl’encompasses straight-chain and branched alkyl groups. They arepreferably straight-chain or branched C₁-C₁₂-alkyl groups, morepreferably C₁-C₈-alkyl groups and particularly preferably C₁-C₄-alkylgroups. Examples of alkyl groups are, in particular, methyl, ethyl,propyl, isopropyl, n-butyl, 2-butyl, sec-butyl, tert-butyl, n-pentyl,2-pentyl, 2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl,1,1-dimethylpropyl, 2,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, 2-hexyl,2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,2-dimethylbutyl,1,3-dimethylbutyl, 2,3-dimethylbutyl, 1,1-dimethylbutyl,2,2-dimethylbutyl, 3,3-dimethylbutyl, 1,1,2-trimethylpropyl,1,2,2-trimethylpropyl, 1-ethylbutyl, 2-ethylbutyl, 1-ethyl-2-methylpropyl, n-heptyl, 2-heptyl, 3-heptyl, 2-ethylpentyl,1-propylbutyl, octyl.

[0031] Substituted alkyl radicals preferably have 1, 2, 3, 4 or 5, inparticular 1, 2 or 3, substituents selected from among cycloalkyl, aryl,hetaryl, halogen, NE¹E², NE¹E²E³⁺, carboxyl, carboxylate, —SO₃H andsulfonate.

[0032] A cycloalkyl group is preferably a C₅-C₇-cycloalkyl group such ascyclopentyl, cyclohexyl and cycloheptyl.

[0033] If the cycloalkyl group is substituted, it preferably has 1, 2,3, 4 or 5, in particular 1, 2 or 3, substituents selected from amongalkyl, alkoxy and halogen.

[0034] Aryl is preferably phenyl, tolyl, xylyl, mesityl, naphthyl,anthracenyl, phenanthrenyl, naphthacenyl, in particular phenyl ornaphthyl.

[0035] Substituted aryl radicals preferably have 1, 2, 3, 4 or 5, inparticular 1, 2 or 3, substituents selected from among alkyl, alkoxy,carboxyl, carboxylate, trifluoromethyl, —SO₃H, sulfonate, NE¹E²,alkylene-NE¹E², nitro, cyano and halogen.

[0036] Hetaryl is preferably pyridyl, quinolinyl, acridinyl,pyridazinyl, pyrimidinyl or pyrazinyl.

[0037] Substituted hetaryl radicals preferably have 1, 2 or 3substituents selected from among alkyl, alkoxy, carboxyl, carboxylate,—SO₃H, sulfonate, NE¹E², alkylene-NE¹E², trifluoromethyl and halogen.

[0038] What has been said above in respect of alkyl, cycloalkyl and arylradicals applies analogously to alkoxy, cycloalkyloxy and aryloxyradicals.

[0039] The radicals NE¹E² and NE⁴E⁵ are preferably N,N-dimethylamino,N,N-diethylamino, N,N-dipropylamino, N,N-diisopropylamino,N,N-di-n-butylamino, N,N-di-t-butylamino, N,N-dicyclohexylamino orN,N-diphenylamino.

[0040] Halogen is fluorine, chlorine, bromine or iodine, preferablyfluorine, chlorine or bromine.

[0041] For the purposes of the present invention, carboxylate andsulfonate are preferably each a derivative of a carboxylic acid functionor a sulfonic acid function, in particular a metal carboxylate orsulfonate, a carboxylic ester or sulfonic ester function or acarboxamide or sulfonamide function. These include, for example, estersof C₁-C₄-alkanoles such as methanol, ethanol, n-propanol, isopropanol,n-butanol, sec-butanol and tert-butanol.

[0042] y¹ and y² are preferably each a radical containing a phosphorusatom and in particular a radical of the formula P(OR⁷)(OR⁸), OP(OR⁷)R⁸or OP(OR⁷)(OR⁸), where

[0043] R⁷ and R⁸ are each, independently of one another, alkyl,cycloalkyl, heterocycloalkyl, aryl or hetaryl which may bear one, two orthree substituents selected from among alkyl, cycloalkyl,heterocycloalkyl, aryl, hetaryl, COOR^(f), COO⁻M⁺, SO₃R^(f), SO⁻ ₃M⁺,NE⁴E⁵, alkylene-NE⁴E⁵, NE⁴E⁵E⁶⁺X⁻, alkylene-NE⁴E⁵E⁶⁺X⁻, OR^(f), SR^(f),(CHR^(g)CH₂O)_(y)R^(f), (CH₂N(E⁴))_(y)R^(f), (CH₂CH₂N(E⁴))_(y)R^(f),halogen, trifluoromethyl, nitro, acyl and cyano,

[0044]  where

[0045] R^(f), E⁴, E⁵ and E⁶ are identical or different radicals selectedfrom among hydrogen, alkyl, cycloalkyl or aryl,

[0046] R^(g) is hydrogen, methyl or ethyl,

[0047] M⁺is a cation,

[0048] X⁻ is an anion, and

[0049] y is an integer from 1 to 120, or

[0050] R⁷ and R⁸ together with the phosphorus atom and the oxygenatom(s) to which they are bound form a 5- to 8-membered heterocycle towhich one, two or three cycloalkyl, heterocycloalkyl, aryl or hetarylgroups may additionally be fused, where the heterocycle and, if present,the fused-on groups may each bear, independently of one another, one,two, three or four substituents selected from among alkyl, cycloalkyl,heterocycloalkyl, aryl, hetaryl, COOR^(f), COO⁻M⁺, SO₃R^(f), SO⁻ ₃M⁺,NE⁴E⁵, alkylene-NE⁴E⁵, NE⁴E⁵E⁶⁺X⁻, alkylene-NE⁴E⁵E⁶⁺X⁻, OR^(f), SR^(f),(CHR^(g)CH₂O)_(y)R^(f), (CH₂N(E⁴))_(y)R^(f), (CH₂CH₂N(E⁴))_(y)R^(f),halogen, trifluoromethyl, nitro, acyl and cyano, where R^(f), R^(g), E⁴,E⁵, E⁶, M⁺, X⁻ and y are as defined above.

[0051] In a preferred embodiment, one of the radicals y¹ or y² or bothradicals y¹ and y² in the formula I are selected from among radicals ofthe formulae P(OR⁷)(OR⁸), OP(OR⁷)R⁸ and OP(OR⁷)(OR⁸) in which R⁷ and R⁸together with the phosphorus atom and the oxygen atom(s) to which theyare bound form a 5- to 8-membered heterocycle to which one, two or threecycloalkyl, heterocycloalkyl, aryl and/or hetaryl groups mayadditionally be fused, where the heterocycle and/or the fused-on groupsmay each, independently of one another, bear one, two, three or foursubstituents selected from among alkyl, alkoxy, halogen, nitro, cyano,carboxyl, SO₃H, sulfonate, NE⁴E⁵, alkylene-NE⁴E⁵ and carboxylate.

[0052] The radicals y¹ and y² are preferably selected from amongphosphonite and/or phosphite radicals of the formula II

[0053] where

[0054] r, s and t are each, independently of one another, 0 or 1 and thesum of r, s and t is at least 2,

[0055] D together with the phosphorus atom and the oxygen atom(s) towhich it is bound form a 5- to 8-membered heterocycle to which one, twoor three cycloalkyl, heterocycloalkyl, aryl and/or hetaryl groups may befused, where the fused-on groups may each bear, independently of oneanother, one, two, three or four substituents selected from among alkyl,alkoxy, halogen, SO₃H, sulfonate, NE⁴E⁵, alkylene-NE⁴E⁵, nitro, cyano,carboxyl and carboxylate, and/or D may have one, two or threesubstituents selected from among alkyl, alkoxy, substituted orunsubstituted cycloalkyl and substituted or unsubstituted aryl, and/or Dmay be interrupted by 1, 2 or 3 substituted or unsubstituted heteroatoms.

[0056] The radical D is preferably a C₂-C₆-alkylene bridge to which 1 or2 aryl groups are fused and/or may have a substituent selected fromamong alkyl, substituted or unsubstituted cycloalkyl and substituted orunsubstituted aryl, and/or may be interrupted by a substituted orunsubstituted hetero atom.

[0057] The fused-on arylene of the radical D is preferably benzene ornaphthalene. Fused-on benzene rings are preferably unsubstituted or have1, 2 or 3, in particular 1 or 2, substituents selected from among alkyl,alkoxy, halogen, SO₃H, sulfonate, NE⁴E⁵, alkylene-NE⁴E⁵,trifluoromethyl, nitro, carboxyl, alkoxycarbonyl, acyl and cyano.Fused-on naphthalenes are preferably unsubstituted or have 1, 2 or 3, inparticular 1 or 2, of the substituents mentioned above for the fused-onbenzene rings in the ring which is not fused on and/or in the fused-onring. An alkyl substituent on the fused-on aryls is preferablyC₁-C₄-alkyl and in particular methyl, isopropyl or tert-butyl. Alkoxy ispreferably C₁-C₄-alkoxy and in particular methoxy. Alkoxycarbonyl ispreferably C₁-C₄-alkoxycarbonyl. Halogen is particularly preferablyfluorine or chlorine.

[0058] If the C₂-C₆-alkylene bridge of the radical D is interrupted by1, 2 or 3 substituted or unsubstituted hetero atoms, these arepreferably selected from among O, S and NR^(h), where R^(h) is alkyl,cycloalkyl or aryl. The C₂-C₆-alkylene bridge of the radical D ispreferably interrupted by one substituted or unsubstituted hetero atom.

[0059] If the C₂-C₆-alkylene bridge of the radical D is substituted, itpreferably has 1, 2 or 3, in particular 1, substituents selected fromamong alkyl, cycloalkyl and aryl, where the aryl substituent may bear 1,2 or 3 of the substituents mentioned for aryl. The alkylene bridge Dpreferably has one substituent selected from among methyl, ethyl,isopropyl, phenyl, p-(C₁-C₄-alkyl)phenyl, preferably p-methylphenyl,p-(C₁-C₄-alkoxy)phenyl, preferably p-methoxyphenyl, p-halophenyl,preferably p-chlorophenyl, and p-trifluoromethylphenyl.

[0060] The radical D is preferably a C₃-C₆-alkylene bridge which isfused and/or substituted and/or interrupted by substituted orunsubstituted hetero atoms as described above. In particular, theradical D is a C₃-C₆-alkylene bridge on to which one or two phenyland/or naphthyl groups are fused, where the phenyl or naphthyl groupsmay bear 1, 2 or 3, in particular 1 or 2, of the abovementionedsubstituents.

[0061] Preference is given to the radical D (i.e. R⁷ and R⁸ together)together with the phosphorus atom and the oxygen atom(s) to which it isbound forming a 5- to 8-membered heterocycle, with the radical D (R⁷ andR⁸ together) being a radical selected from among the radicals of theformulae II.1 to II.5,

[0062] where

[0063] z is O, S or NR^(i), where

[0064]  R^(i) is alkyl, cycloalkyl or aryl,

[0065] or Z is a C₁-C₃-alkylene bridge which may have a double bondand/or an alkyl, cycloalkyl or aryl substituent, where the arylsubstituent may bear one, two or three of the substituents mentioned foraryl,

[0066] or Z is a C₂-C₃-alkylene bridge which is interrupted by O, S orNR^(i),

[0067] R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵ and R¹⁶ are each, independentlyof one another, hydrogen, alkyl, cycloalkyl, aryl, alkoxy, halogen,SO₃H, sulfonate, NE⁴E⁵, alkylene-NE⁴E⁵, trifluoromethyl, nitro,alkoxycarbonyl, carboxyl or cyano.

[0068] D is preferably a radical of the formula II.1 in which R⁹ and R¹⁰are each hydrogen.

[0069] D is preferably a radical of the formula II.2a

[0070] where

[0071] R⁹ is hydrogen, C₁-C₄-alkyl, C₁-C₄-alkoxy, SO₃H, sulfonate,NE⁴E⁵, alkylene-NE⁴E⁵, preferably hydrogen, C₁-C₄-alkyl or C₁-C₄-alkoxy,in particular methyl, methoxy, isopropyl or tert-butyl,

[0072] R¹⁰ is hydrogen, C₁-C₄-alkyl, preferably methyl, isopropyl ortert-butyl, C₁-C₄-alkoxy, preferably methoxy, fluorine, chlorine ortrifluoromethyl. R¹⁰ may also be SO₃H, sulfonate, NE⁴E⁵ oralkylene-NE⁴E⁵.

[0073] D is prefeably a radical of the formula II.3a

[0074] where

[0075] R⁹ and R¹⁰ are as defined for the formula II.2a,

[0076] R¹ is hydrogen, C₁-C₄-alkyl, preferably methyl or ethyl, phenyl,p-(C₁-C₄-alkoxy)phenyl, preferably p-methoxyphenyl, p-fluorophenyl,p-chlorophenyl or p-(trifluoromethyl)phenyl.

[0077] D is preferably a radical of the formula II.4 in which R⁹, R¹⁰,R¹¹, R¹², R¹³, R¹⁴, R¹⁵ and R¹⁶ are each hydrogen.

[0078] D is preferably a radical of the formula II.4 in which R⁹, R¹⁰,R¹¹, R¹², R¹⁴ and R¹⁶ are each hydrogen and the radicals R¹³ and R¹⁵ areeach, independently of one another, alkoxycarbonyl, preferablymethoxycarbonyl, ethoxycarbonyl, n-propyloxycarbonyl orisopropyloxycarbonyl. In particular, the radicals R¹³ and R¹⁵ arelocated in the ortho position relative to the phosphorus atom or oxygenatom.

[0079] D is preferably a radical of the formula II.5 in which R⁹, R¹⁰,R¹¹, R¹², R¹³, R¹⁴, R¹⁵ and R¹⁶ are each hydrogen and Z is CR^(l), whereR¹ is as defined above.

[0080] D is preferably a radical of the formula II.5 in which R⁹, R¹⁰,R¹¹, R¹², R¹⁴ and R¹⁶ are each hydrogen, Z is CR^(h) and the radicalsR¹³ and R¹⁵ are each, independently of one another, alkoxycarbonyl,preferably methoxycarbonyl, ethoxycarbonyl, n-propyloxycarbonyl orisopropyloxycarbonyl. In particular, the radicals R¹³ and R¹⁵ arelocated in the ortho position relative to the phosphorus atom or oxygenatom.

[0081] In a further, preferred embodiment, one of the radicals y¹ or y²or both radicals y¹ and y² in the formula I are selected from amongradicals of the formulae P(OR⁷)(OR⁸), OP(OR⁷)R⁸ and OP(OR⁷)(OR⁸) inwhich R⁷ and R⁸ do not together form a heterocycle.

[0082] The radicals R⁷ and R⁸ are preferably each, independently of oneanother, alkyl, aryl or hetaryl which may bear one, two or threesubstituents selected from among alkyl (only for aryl or hetaryl),cycloalkyl, aryl, alkoxy, cycloalkoxy, aryloxy, halogen,trifluoromethyl, nitro, cyano, carboxyl, carboxylate, acyl, —SO₃H,sulfonate, NE⁴E⁵ and alkylene-NE⁴E⁵, where E⁴ and E⁵ are identical ordifferent and are selected from among alkyl, cycloalkyl and aryl.

[0083] The radicals R⁷ and R⁸ are preferably selected independently fromamong the radicals of the formulae II.6 and II.7

[0084] where

[0085] R⁹ and R¹⁰ are each, independently of one another, hydrogen,C₁-C₄-alkyl, COOR^(f), COO⁻M⁺, SO₃R^(d), SO₃ ⁻M⁺, NE⁴E⁵, alkylene-NE⁴E⁵,NE⁴E⁵E⁶⁺X⁻, alkylene-NE⁴E⁵E⁶⁺X⁻, C₁-C₄-alkoxy, halogen ortrifluoromethyl, where R^(f), E⁴, E⁵ and E⁶ may be identical ordifferent and are each hydrogen, alkyl, cycloalkyl or aryl, M⁺is acation and X⁻ is an anion.

[0086] In the formulae II.6 and II.7, the radicals R⁹ and R¹⁰ arepreferably each, independently of one another, hydrogen, C₁-C₄-alkyl orC₁-C₄-alkoxy, in particular methyl, methoxy, isopropyl or tert-butyl.

[0087] A¹ and A² are preferably each, independently of one another, O, Sand CR⁵R⁶, where R⁵ and R⁶ are each, independently of one another,hydrogen, alkyl, cycloalkyl, aryl or hetaryl. In particular, R⁵ and R⁶are each, independently of one another, hydrogen or C₁-C₄-alkyl such asmethyl, ethyl, n-propyl, n-butyl or tert-butyl. In particular, R⁵ and R⁶are both methyl.

[0088] Preference is given to one of the radicals A¹ or A² being O or Sand the other being CR⁵R⁶. More preferably, the radicals A¹ and A² areselected from among O and S.

[0089] The radicals R¹, R², R³ and R⁴ are preferably selected from amonghydrogen, alkyl, cycloalkyl, aryl and hetaryl. Preference is given to R¹and R³ being hydrogen and R² and R⁴ being C₁-C₄-alkyl such as methyl,ethyl, n-propyl, n-butyl or tert-butyl.

[0090] At least one of the radicals R¹, R², R³ and/or R⁴ is preferably apolar (hydrophilic) group, which then generally results in water-solublecatalysts. The polar groups are preferably selected from among COOR^(d),COO⁻M⁺, SO₃R^(d), SO⁻ ₃M⁺, NE¹E², alkylene-NE¹E², NE¹E²E³⁺X⁻,alkylene-NE¹E²E³⁺X⁻, OR^(d), SR^(d), (CHR^(e)CH₂O)_(x)R^(d) or(CH₂CH₂N(E¹))_(x)R^(d), where R^(d), E¹, E², E³, R^(d), R^(e), M⁺, X⁻and x are as defined above.

[0091] R¹, R², R³ and R⁴ are particularly preferably each hydrogen.

[0092] If R¹ and/or R³ form a fused-on ring system, the fused-on groupsare preferably benzene or naphthalene groups. Fused-on benzene rings arepreferably unsubstituted or have 1, 2 or 3, in particular 1 or 2,substituents selected from among alkyl, alkoxy, halogen, SO₃H,sulfonate, NE⁴E⁵, alkylene-NE⁴E⁵, trifluoromethyl, nitro, carboxyl,alkoxycarbonyl, acyl and cyano. Fused-on naphthalenes are preferablyunsubstituted or have 1, 2, or 3, in particular 1 or 2, of thesubstituents mentioned above for the fused-on benzene rings in the ringwhich is not fused on and/or in the fused-on ring.

[0093] M⁺is preferably an alkali metal cation, e.g. Li⁺, Na⁺or K⁺, NH₄⁺or a quarternary ammonium compound as is obtainable by protonation orquaternization of amines.

[0094] X⁻ is preferably halide, particularly preferably Cl- or Br-.

[0095] In a preferred embodiment of the process of the presentinvention, use is made of a hydroformylation catalyst in which thecompound of the formula I is selected from among the compounds of theformulae I.1 to I.6

[0096] where

[0097] A¹ is O, S or CR⁵R⁶, where R⁵ and R⁶ are each, independently ofone another, hydrogen or C₁-C₄-alkyl, in particular methyl ortert-butyl,

[0098] R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³ and R²⁴ are each, independentlyof one another,

[0099]  hydrogen, alkyl, preferably C₁-C₄-alkyl, in particular methyl ortert-butyl, cycloalkyl, heterocycloalkyl, aryl, hetaryl, COOR^(d),COO⁻M⁺, SO₃R^(f), SO⁻ ₃M⁺, NE⁴E5, alkylene-NE⁴E⁵, NE⁴E⁵E⁶⁺X⁻,alkylene-NE⁴E⁵E⁶⁺X⁻, OR^(f), preferably C₁-C₄-alkoxy, in particularmethoxy, SR^(f), (CHR^(g)CH₂O)_(y)R^(f), (CH₂N(E⁴))_(y)R^(f),(CH₂CH₂N(E⁴))_(y)R^(f), halogen, trifluoromethyl, nitro, acyl and cyano,

[0100]  where

[0101] R^(f), E⁴, E⁵ and E⁶ are identical or different radicals selectedfrom among hydrogen, alkyl, preferably C₁-C₄-alkyl, in particular methylor tert-butyl, alkoxy, preferably methoxy, cycloalkyl and aryl,

[0102] R^(g) is hydrogen, methyl or ethyl,

[0103] M⁺is a cation,

[0104] X⁻ is an anion, and

[0105] y is an integer from 1 to 120.

[0106] The invention further provides compounds of the formula I

[0107] where

[0108] A¹ and A² are each, independently of one another, O, S,SiR^(a)R^(b), NR^(c) or CR⁵R⁶, with the exception of A¹=S and A²=O,where

[0109] R^(a), R^(b), R^(c), R⁵ and R⁶ are each, independently of oneanother, hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl,

[0110] y¹ and y² are each, independently of one another, radicalscontaining at least one phosphorus, arsenic or antimony atom, where ineach case at least two substituted or unsubstituted heteroatoms selectedfrom among O, S and NR^(c), where R^(c) is hydrogen, alkyl, cycloalkylor aryl, are directly bound to the phosphorus, arsenic or antimony atom,and

[0111] R¹, R², R³ and R⁴ are each, independently of one another,hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl, hetaryl, COOR^(d),COO⁻M⁺, SO₃R^(d), SO⁻ ₃M⁺, NE¹E², NE¹E²E³⁺X⁻, alkylene-NE¹E²E³⁺X⁻,OR^(d), SR^(d), (CHR^(e)CH₂O)_(x)R^(d), (CH₂N(E¹))_(x)R^(d),(CH₂CH₂N(E¹))_(x)R^(d), halogen, trifluoromethyl, nitro, acyl or cyano,

[0112]  where

[0113] R^(d), E¹, E² and E³ are identical or different radicals selectedfrom among hydrogen, alkyl, cycloalkyl and aryl,

[0114] R^(e) is hydrogen, methyl or ethyl,

[0115] M⁺is a cation,

[0116] X⁻ is an anion, and

[0117] x is an integer from 1 to 120, or

[0118] R¹ and/or R³ together with two adjacent carbon atoms of thebenzene ring to which they are bound form a fused ring system having 1,2 or 3 further rings.

[0119] As regards preferred embodiments of the compounds of the formulaI, reference may be made to what has been said above in respect of theligands of the formula I used in the hydroformylation process of thepresent invention.

[0120] The invention further provides a catalyst comprising at least onecomplex of a metal of transition group VIII with at least one novelcompound of the formula I as defined above.

[0121] The catalysts of the present invention and those used accordingto the present invention may comprise one or more of the compounds ofthe formula I as ligands. In addition to the above-described ligands ofthe formula I, they may further comprise at least one additional ligandselected from among halides, amines, carboxylates, acetylacetonate,arylsulfonates and alkylsulfonates, hydride, CO, olefins, dienes,cycloolefins, nitriles, N-containing heterocycles, aromatics andheteroaromatics, ethers, PF₃, phospholes, phosphabenzenes andmonodentate, bidentate and polydentate phosphine, phosphinite,phosphonite, phosphoramidite and phosphite ligands.

[0122] The metal of transition group VIII is preferably cobalt,ruthenium, rhodium, palladium, platinum, osmium or iridium, inparticular cobalt, rhodium, ruthenium or iridium.

[0123] The preparation of the compounds of the formula I used accordingto the present invention and the novel compounds of the formula I can becarried out, for example, starting from a compound of the formula I.a

[0124] where

[0125] Y^(a) and y^(b) are each, independently of one another, a radicalY¹ or y² as defined above, or y^(a) and y^(b) are each, independently ofone another, halogen, OH, OC(O)CF₃ or SO₃Me where Me=hydrogen, Li, Na orK, and y^(a) and/or y^(b) may also be hydrogen if at least one of theradicals R² and/or R⁴ is hydrogen, an alkoxy group or an alkoxycarbonylgroup located in the ortho position relative to y^(a) and/or y^(b), and

[0126] A¹, A², R¹, R², R³ and R⁴ are as defined above.

[0127] The functionalization of the radicals y^(a) and y^(b) to form theradicals y¹ and y² can be carried out in a manner analogous to knownmethods. For example, compounds of the formula I.a in which y^(a) andy^(b) are halogen, preferably chlorine, can firstly be lithiated and theintermediate formed can be reacted with a compound which bears a halogenatom, preferably a chlorine atom, on the phosphorus atom, for example acompound of the formula Cl-P(OR⁷)₂, Cl-P(OR⁷)(OR⁸) or Cl-P(OR⁷)₂. Thenovel compounds I in which y¹ and y² are each a radical of the formulaII in which t=0 are prepared by, for example, reaction of I.a withcompounds of the formula II.a according to the following scheme,

[0128] where r, s and D are as defined above for the compounds of theformula II.

[0129] In place of compounds of the formula I.a in whichy^(a)=y^(b)=halogen, it is also possible to lithiate compounds I.a inwhich y^(a)=y^(b)=hydrogen and in which hydrogen, an alkoxy group or analkoxycarbonyl group is present in each of the ortho positions relativeto y^(a) and y^(b). Such reactions are described in the literature underthe name “Ortho-Lithiation” (see, for example, D. W. Slocum, J. Org.Chem., 1976, 41, 3652-3654; J. M. Mallan, R. L. Bebb, Chem. Rev., 1969,693 ff; V. Snieckus, Chem. Rev., 1980, 6, 879-933). The organolithiumcompounds obtained in this way can then be reacted with the phosphorushalide compounds in the manner indicated above to form the targetcompounds I.

[0130] The arsenic compounds I and the antimony compounds I can beprepared in an analogous way.

[0131] In general, the catalysts or catalyst precursors used in eachcase are converted under hydroformylation conditions into catalyticallyactive species of the formula H_(x)M_(y)(CO)_(z)L_(q), where M is ametal of transition group VIII, L is a phosphorus-, arsenic- orantimony-containing compound of the formula I and q, x, y, z areintegers which depend on the valence and type of the metal and also thenumber of coordination positions occupied by the ligand L. z and q arepreferably, independently of one another, at least 1, e.g. 1, 2 or 3.The sum of z and q is preferably from 2 to 5. If desired, the complexesmay further comprise at least one of the above-described additionalligands.

[0132] In a preferred embodiment, the hydroformylation catalysts areprepared in situ in the reactor used for the hydroformylation reaction.However, if desired, the catalysts used according to the presentinvention can also be prepared separately and isolated by customarymethods. To prepare the catalysts used according to the presentinvention in situ, it is possible, for example, to react at least onecompound of the formula I, a compound or a complex of a metal oftransition group VIII, if desired at least one further additional ligandand, if desired, an activating agent in an inert solvent under thehydroformylation conditions.

[0133] Suitable rhodium compounds or complexes are, for example,rhodium(II) and rhodium(III) salts, e.g. rhodium(III) chloride,rhodium(III) nitrate, rhodium(III) sulfate, potassium rhodium sulfate,rhodium(II) and rhodium(III) carboxylates, rhodium(II) and rhodium(III)acetate, rhodium(III) oxide, salts of rhodic(III) acid, trisammoniumhexachlororhodate(III), etc. Also suitable are rhodium complexes such asdicarbonylrhodium acetylacetonate, acetylacetonatobisethylenerhodium(I),etc. Preference is given to using dicarbonylrhodium acetylacetonate orrhodium acetate.

[0134] Ruthenium salts or compounds are likewise suitable. Suitableruthenium salts are, for example, ruthenium(III) chloride,ruthenium(IV), ruthenium(VI) or ruthenium(VIII) oxide, alkali metalsalts of ruthenium oxo acids such as K₂RuO₄ or KRuO₄ or complexes suchas RuHCl(CO)(PPh₃)₃. It is also possible to use the carbonyls ofruthenium, e.g. dodecacarbonyltriruthenium oroctadecacarbonylhexaruthenium, or mixed forms in which Co has beenpartially replaced by ligands of the formula PR₃, e.g. Ru(CO)₃(PPh₃)₂,in the process of the present invention.

[0135] Suitable cobalt compounds are, for example cobalt(II) chloride,cobalt(II) sulfate, cobalt(II) carbonate, cobalt(II) nitrate, theiramine or hydrate complexes, cobalt carboxylates such as cobalt acetate,cobalt ethylhexanoate, cobalt naphthanoate, and also the caprolactamatecomplex of cobalt. Here too, the carbonyl complexes of cobalt, e.g.octacarbonyldicobalt, dodecacarbonyltetracobalt andhexadecacarbonylhexacobalt, can be used.

[0136] The abovementioned and further suitable compounds of cobalt,rhodium, ruthenium and iridium are known in principle and are adequatelydescribed in the literature or they can be prepared by a person skilledin the art using methods analogous to those for known compounds.

[0137] Suitable activating agents are, for example, Brönsted acids,Lewis acids, e.g. BF₃, AlCl₃, ZnCl₂, and Lewis bases.

[0138] As solvents, preference is given to using the aldehydes which areformed in the hydroformylation of the respective olefins, and also theirhigher-boiling downstream reaction products, e.g. the products of thealdol condensation. Further suitable solvents are aromatics such astoluene and xylenes, hydrocarbons or mixtures of hydrocarbons, also fordilution of the abovementioned aldehydes and the downstream products ofthe aldehydes. Further solvents are esters of aliphatic carboxylic acidswith alkanoles, for example ethyl acetate or Texanol™, ethers such astert-butyl methyl ether and tetrahydrofuran. In the case of sufficientlyhydrophilic ligands, it is also possible to use alcohols such asmethanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol,ketones, such as acetone and methyl ethyl ketone etc.

[0139] “Ionic liquids” can also be used as solvents. These are liquidsalts, for example N,N'-dialkylimidazolium salts such asN-butyl-N'-methylimidazolium salts, tetraalkylammonium salts such astetra-n-butylammonium salts, N-alkylpyridinium salts such asn-butylpyridinium salts, tetraalkylphosphonium salts such astrishexyl(tetradecyl)phosphonium salts, e.g. the tetrafluoroborates,acetates, tetrachloroaluminates, hexafluorophosphates, chlorides andtosylates.

[0140] Furthermore, the reactions can also be carried out in water oraqueous solvent systems comprising water together with a water-misciblesolvent, for example an alcohol such as methanol, ethanol, n-propanol,isopropanol, n-butanol, isobutanol, a ketone such as acetone or methylethyl ketone or another solvent. For this purpose, use is made ofligands of the formula I which have been modified with polar groups, forexample ionic groups such as SO₃Me, CO₂Me where Me=Na, K or NH₄, or suchas N(CH₃)₃ ⁺. The reactions then occur as a two-phase catalysis in whichthe catalyst is present in the aqueous phase and starting materials andproducts form the organic phase. The reaction in the “ionic liquids” canalso be carried out as a two-phase catalysis.

[0141] The molar ratio of phosphorus-containing ligand to metal oftransition group VIII is generally in a range from about 1:1 to 1000:1.

[0142] Suitable substrates for the hydroformylation process of thepresent invention are in principle all compounds which contain one ormore ethylenically unsaturated double bonds. These include, for example,olefins such as α-olefins, internal straight-chain and internal branchedolefins. Suitable α-olefins are, for example, ethylene, propene,1-butene, 1-pentene, 1-hexene, 1-heptene,-l-octene, 1-nonene, 1-decene,1-undecene, 1-dodecene, etc.

[0143] Preferred branched, internal olefins are C₄-C₂₀-olefins such as2-methyl-2-butene, 2-methyl-2-pentene, 3-methyl-2-pentene, branched,internal heptene mixtures, branched, internal octene mixtures, branched,internal nonene mixtures, branched, internal decene mixtures, branched,internal undecene mixtures, branched, internal dodecene mixtures, etc.

[0144] Further suitable olefins for the hydroformylation areC₅-C₈-cycloalkenes such as cyclopentene, cyclohexene, cycloheptene,cyclooctene and their derivatives, e.g. their C₁-C₂₀-alkyl derivativeshaving from 1 to 5 alkyl substituents. Olefins suitable forhydroformylation also include vinyl aromatics such as styrene,α-methylstyrene, 4-isobutylstyrene, etc. Other suitable olefins for thehydroformylation are α,β-ethylenically unsaturated monocarboxylic and/ordicarboxylic acids, their esters, monoesters and amides, e.g. acrylicacid, methacrylic acid, maleic acid, fumaric acid, crotonic acid,itaconic acid, methyl 3-penteneoate, methyl 4-penteneoate, methyloleate, methyl acrylate, methyl methacrylate, unsaturated nitriles suchas 3-pentenenitrile, 4-pentenenitrile, acrylonitrile, vinyl ethers suchas vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, etc.,C₁-C₂₀-alkenols, -alkenediols and -alkadienoles, e.g. 2,7-octadien-1-ol.Further suitable substrates are dienes or polyenes containing isolatedor conjugated double bonds. These include, for example, 1,3-butadiene,1,4-pentadiene, 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene,vinylcyclohexene, dicyclopentadiene, 1,5,9-cyclooctatriene and alsohomopolymers and copolymers of butadiene.

[0145] The unsaturated compound used for the hydroformylation ispreferably selected from among internal linear olefins and olefinmixtures in which at least one internal linear olefin is present.Preferred linear (straight-chain) internal olefins are C₄-C₂₀-olefinssuch as 2-butene, 2-pentene, 2-hexene, 3-hexene, 2-heptene, 3-heptene,2-octene, 3-octene, 4-octene, etc., and mixtures thereof.

[0146] In the hydroformylation process of the present invention,preference is given to using an olefin mixture which is available on anindustrial scale and comprises, in particular, at least one internallinear olefin. These include, for example, the Ziegler olefins obtainedby controlled ethene oligomerization in the presence of alkylaluminumcatalysts. These are essentially unbranched olefins having a terminaldouble bond and an even number of carbon atoms. Further examples are theolefins obtained by ethene oligomerization in the presence of variouscatalyst systems, e.g. the predominantly linear α-olefins obtained inthe presence of alkylaluminum chloride/titanium tetrachloride catalystsand the α-olefins obtained by the Shell Higher Olefin Process (SHOP) inthe presence of nickel-phosphine complexes as catalysts. Furthersuitable industrially available olefin mixtures are obtained in theparaffin dehydrogenation of appropriate petroleum fractions, e.g.kerosene or diesel oil fractions. To convert paraffins, predominantlyn-paraffins, into olefins, essentially three processes are used:

[0147] thermal cracking (steam cracking),

[0148] catalytic dehydrogenation and

[0149] chemical dehydrogenation by chlorination and dehydrochlorination.

[0150] Thermal cracking leads predominantly to α-olefins, while theother variants produce olefin mixtures which generally also haverelatively high proportions of olefins containing an internal doublebond. Further suitable olefin mixtures are the olefins obtained inmetathesis or telomerization reactions. They include, for example, theolefins from the Phillips triolefin process, a modified SHOP comprisingethylene oligomerization, double bond isomerization and subsequentmetathesis (ethenolysis).

[0151] Further suitable industrial olefin mixtures which can be used inthe hydroformylation process of the present invention are selected fromamong dibutenes, tributenes, tetrabutenes, dipropenes, tripropenes,tetrapropenes, mixtures of butene isomers, in particular raffinate II,dihexenes, dimers and oligomers from the Dimersol® process of IFP, theOctol® process of Hüls, the Polygas process, etc.

[0152] Preference is given to a process in which the hydroformylationcatalyst is prepared in situ by reacting at least one compound of theformula I, a compound or a complex of a metal of transition group VIIIand, if desired, an activating agent in an inert solvent under thehydroformylation conditions.

[0153] The hydroformylation reaction can be carried out continuously,semicontinuously or batchwise.

[0154] Suitable reactors for the continuous reaction are known to thoseskilled in the art and are described, for example, in UllmannsEnzyklopädie der technischen Chemie, Vol. 1, 3rd Edition, 1951, p. 743ff.

[0155] Suitable pressure-rated reactors are likewise known to thoseskilled in the art and are described, for example, in UllmannsEnzyklopädie der technischen Chemie, Vol. 1, 3rd Edition, 1951, p. 769ff. In general, the process of the present invention is carried outusing an autoclave which may, if desired, be provided with a stirrer andan internal lining.

[0156] The composition of the synthesis gas comprising carbon monoxideand hydrogen used in the process of the present invention can varywithin a wide range. The molar ratio of carbon monoxide to hydrogen isgenerally from about 5:95 to 70:30, preferably from about 40:60 to60:40. Particular preference is given to using a molar ratio of carbonmonoxide to hydrogen in the region of about 1:1.

[0157] The temperature in the hydroformylation reaction is generally ina range from about 20 to 180° C., preferably from about 50 to 150° C.The reaction is generally carried out at the partial pressure of thereaction gas at the reaction temperature chosen. The pressure isgenerally in a range from about 1 to 700 bar, preferably from 1 to 600bar, in particular from 1 to 300 bar. The reaction pressure can bevaried as a function of the activity of the hydroformylation catalystused. In general, the catalysts based on phosphorus-, arsenic- orantimony-containing compounds which are used according to the presentinvention allow reaction in a low pressure range, for example in therange from 1 to 100 bar.

[0158] The hydroformylation catalysts of the present invention and thoseused according to the present invention can be separated from the outputfrom the hydroformylation reaction by customary methods known to thoseskilled in the art and can generally be reused for the hydroformylation.

[0159] The above-described novel catalysts which comprise chiralcompounds of the formula I are suitable for enantioselectivehydroformylation.

[0160] The above-described catalysts can also be immobilized on asuitable support, e.g. made of glass, silica gel, synthetic resins,etc., in a suitable manner, e.g. by binding via functional groupssuitable as anchor groups, adsorption, grafting, etc. They are then alsosuitable for use as solid-phase catalysts.

[0161] Surprisingly, the hydroformylation activity of catalysts based onphosphine ligands of the formula I is generally higher than the activityin respect of isomerization to form internal double bonds. The catalystsof the present invention and those used according to the presentinvention advantageously display a high selectivity to α-aldehydes orα-alcohols in the hydroformylation of α-olefins. In addition, thehydroformylation of internal linear olefins (isomerizinghydroformylation) generally also gives good yields of α-aldehydes or-alcohols and in particular n-aldehydes or -alcohols. Furthermore, thesecatalysts generally have a high stability under hydroformylationconditions, so that they generally make it possible to achieve longercatalyst operating lives than are achieved using the catalysts based onconventional chilating ligands known from the prior art. Furthermore,the catalysts of the present invention and those used according to thepresent invention advantageously display a high activity, so that thecorresponding aldehydes or alcohols are generally obtained in goodyields. In the hydroformylation of α-olefins and also of internal,linear olefins, they also display a very low selectivity to thehydrogenation product of the olefin used.

[0162] The invention further provides for the use of catalystscomprising at least one complex of a metal of transition group VIII withat least one compound of the formula I, as described above, forhydroformylation, carbonylation and hydrogenation.

[0163] The invention is illustrated by the nonrestrictive examplesbelow.

EXAMPLES

[0164] The following ligands were used for hydroformylation:

[0165] I. Preparation of the Ligands

[0166] I.1 Preparation of Ligand D

[0167] Preparation of2,2′-dihydroxy-3,3′-di-tert-butyl-5,5′-dimethoxy-1, 1′-biphenyl

[0168] In a 1000 ml flask fitted with dropping funnel and largeegg-shaped stirrer, 10 g of 3-tert-butyl-4-hydroxyanisole are dissolvedin 300 ml of methanol. Over the course of one hour, a solution of 1.07 gof KOH and 18.3 g of K₃(Fe(CN)₆) in 300 ml of water is added dropwise.As the point of introduction, the solution becomes blue and the mixtureacquires a pink mother-of-pearl color with salt precipitation. Themixture is stirred for another two hours at room temperature. 200 ml ofwater are then added, resulting in partial dissolution of the whiteprecipitate. The suspension is transferred to a 2 l separating funneland extracted twice with 500 ml each time of ethyl acetate. The aqueoussolution is extracted once with 150 ml of ether and the combined organicphases are washed with 200 ml of saturated NaCl solution and dried overNa₂SO₄. Removal of the solvent on a rotary evaporator gives 9.8 g of alight-brown solid. Washing the crude product with n-hexane gives a whitepowder. The yield based on the light-brown powder was 100% of theory.

[0169] Preparation ofdibenzo[d,f]-2,2′-di-tert-butyl-4,4′-dimethoxy-[1,3,2]-dioxyphosphochloride

[0170] The2,2′-dihydroxy-3,3′-di-tert-butyl-5,5′-dimethoxy-1,1′-biphenyl was freedof oxidation products by washing with small amounts of ethyl acetate. 10g (27.9 mmol) of the biphenyl were placed in a 500 ml flask fitted witha condenser and dried azeotropically three times using 10 ml of tolueneeach time and subsequently dissolved in 110 ml of toluene. A catalyticamount (0.24 g) of N-methylpyrrolidone (NMP) was subsequently added. Oneequivalent of PCl₃ (6.29 g) was added via a septum. The solution washeated at 95° C. for 24 hours, with a constant stream of argon gas beingpassed through the apparatus to remove the HCl liberated. Via a T-pieceat the top of the condenser, the HCl-containing stream of argon waspassed into an alcoholic KOH solution. After the reaction was complete,the toluene and any traces of PCl₃ present were taken off, giving abrown oil. After addition of 10 ml of fresh toluene, the product wasdried by means of a high vacuum pump, giving a dry brown powder. Thephosphonite obtained was stored under argon in a Schlenk tube at −20° C.The yield of the light-brown powder was 100% of theory.

[0171] Preparation of Ligand D

[0172] This was prepared by reacting 9,9-dimethylxanthene withdibenzo[d,f]-2,2′-di-tert-butyl-4,4′-dimethoxy-[1,3,2]-dioxaphosphochloride.

[0173] II. Hydroformylations

Example 1

[0174] Hydroformylation of 1-octene Using Ligand A

[0175] 0.79 mg of dicarbonylrhodium acetylacetonate and 16.5 mg ofligand A (60 ppm of Rh, ligand/metal ratio=6.1:1) were weighed outseparately, each dissolved in 1.3 g of toluene, mixed and treated at100° C. with a synthesis gas mixture of CO/H₂ (1:1) at 10 bar in a 300ml steel autoclave provided with a sparging stirrer. After 30 minutes,the autoclave was depressurized, 2.6 g of 1-octene were then added andthe mixture was hydroformylated at 100° C. and 10 bar for another 4hours. The conversion was 98%, the aldehyde selectivity was 48% and thelinearity was 81%. The proportion of a-isomers (n-aldehyde andisoaldehyde) was 96%.

Example 2

[0176] Hdroformylation of 2-butene Using Ligand A

[0177] 3 mg of dicarbonylrhodium acetylacetonate and 63.4 mg of ligand A(60 ppm of Rh, ligand/metal ratio=6.2:1) were weighed out separately,each dissolved in 5 g of toluene, mixed and treated at 100° C. with asynthesis gas mixture of CO/H₂ (1:1) at 10 bar in a 300 ml steelautoclave provided with a sparging stirrer. After 30 minutes, theautoclave was cooled and depressurized, 10 g of 2-butene were theninjected and a pressure of 5 bar of CO/H₂ (1:1) was set at ambienttemperature. The autoclave was subsequently heated to 140° C. andhydroformylation was carried out for 4 hours. During the reaction,further synthesis gas was introduced to maintain a constant pressure.After the reaction was complete, the autoclave was depressurized, withthe gas released being passed through a cold trap and the products fromthe reactor and the cold trap being analyzed by means of gaschromatography. The aldehyde selectivity was 93% and the linearity was69%.

Example 3

[0178] Hydroformylation of 1-octene Using Ligand B

[0179] The procedure of Example 1 was repeated using 0.79 mg ofdicarbonylrhodium acetylacetonate and 16.6 mg of ligand B (60 ppm of Rh,ligand/metal ratio=5:1), each in 1.3 g of toluene, and 2.6 g of 1-octenefor the hydroformylation. The conversion was 99%, the aldehydeselectivity was 91% and the linearity was 88%. The proportion of aproduct was 98%.

Example 4

[0180] Hydroformylation of 1-octene Using Ligand B

[0181] The procedure of Example 1 was repeated using 0.79 mg ofdicarbonylrhodium acetylacetonate and 16.6 mg of ligand B (60 ppm of Rh,ligand/metal ratio=5:1), each in 1.3 g of toluene, and 2.6 g of 1-octenefor the hydroformylation. The temperature during the hydroformylationwas 80° C. The conversion was 97%, the aldehyde selectivity was 90% andthe linearity was 90%. The proportion of a product was 100%.

Example 5

[0182] Hydroformylation of 2-butene Using Ligand B

[0183] The procedure of Example 2 was repeated using 3 mg ofdicarbonylrhodium acetylacetonate and 126 mg of ligand B (60 ppm of Rh,ligand/metal ratio=9.9:1), each in 5 g of toluene, and 10 g of 2-butenefor the hydroformylation. The conversion was 66%, the aldehydeselectivity was 94% and the linearity was 66%.

Example 6

[0184] Hydroformylation of 1-octene Using Ligand C

[0185] The procedure of Example 1 was repeated using 0.93 mg ofdicarbonylrhodium acetylacetonate and 19.6 mg of ligand C (60 ppm of Rh,ligand/metal ratio=5:1), each in 1.55 g of xylene, and 3.1 g of 1-octenewere used for the hydroformylation. The temperature during thehydroformylation was 90° C. The conversion was 89% and the linearity was81%. The proportion of a products was 100%.

Example 7

[0186] Hydroformylation of 1-octene Using Ligand D

[0187] The procedure of Example 1 was repeated using 0.78 mg ofdicarbonylrhodium acetylacetonate and 14.9 mg of ligand D (60 ppm of Rh,ligand/metal ratio=5:1), each in 1.3 g of xylene, and 2.6 g of 1-octenefor the hydroformylation. The temperature during the hydroformylationwas 80° C. The conversion was 53%, the aldehyde selectivity was 30% andthe linearity was 82%. The proportion of a product was 100%.

Example 8

[0188] Hydroformylation of 1-octene Using Ligand E

[0189] The procedure of Example 1 was repeated using 0.87 mg ofdicarbonylrhodium acetylacetonate and 17.1 mg of ligand E (60 ppm of Rh,ligand/metal ratio=5:1), each in 1.45 g of xylene, and 2.9 g of 1-octenefor the hydroformylation. The temperature during the hydroformylationwas 90° C. The conversion was 49%, the aldehyde selectivity was 94% andthe linearity was 88%. The proportion of a product was 100%.

Example 9

[0190] Hydroformylation of 1-octene Using Ligand F

[0191] The procedure of Example 1 was repeated, except that ligand F wasused instead of ligand A, the molar ratio of carbon monoxide to hydrogenwas 1:2, the temperature was 90° C., the pressure was 5 bar, thereaction time was 4 hours. The conversion was 36%, the aldehydeselectivity was 47% and the linearity was 96%.

Example 10

[0192] Hydroformylation of 1-octene Using Ligand F

[0193] The procedure of Example 1 was repeated, except that ligand F wasused instead of ligand A, the molar ratio of carbon monoxide to hydrogenwas 1:2, the temperature was 120° C., the pressure was 10 bar, thereaction time was 4 hours. The conversion was 92%, the aldehydeselectivity was 33% and the linearity was 94%.

We claim:
 1. A process for the hydroformylation of compounds containingat least one ethylenically unsaturated double bond by reaction withcarbon monoxide and hydrogen in the presence of a hydroformylationcatalyst comprising at least one complex of a metal of transition groupVIII with at least one ligand selected from among compounds of thegeneral formula I

where A¹ and A² are each, independently of one another, O, S,SiR^(a)R^(b), NR^(c) or CR⁵R⁶, where R^(a), R^(b), R^(c), R⁵ and R⁶ areeach, independently of one another, hydrogen, alkyl, cycloalkyl,heterocycloalkyl, aryl or hetaryl, Y¹ and y² are each, independently ofone another, radicals containing at least one phosphorus, arsenic orantimony atom, where in each case at least two substituted orunsubstituted heteroatoms selected from among O, S and NR^(c), whereR^(c) is hydrogen, alkyl, cycloalkyl or aryl, are directly bound to thephosphorus, arsenic or antimony atom, and R¹, R², R³ and R⁴ are each,independently of one another, hydrogen, alkyl, cycloalkyl,heterocycloalkyl, aryl, hetaryl, COOR^(d), COO⁻M⁺, SO₃R^(d), SO⁻ ₃M⁺,NE¹E², NE¹E²E³⁺X⁻, alkylene-NE¹E²E³⁺X⁻, OR^(d), SR^(d),(CHR^(e)CH₂O)_(x)R^(d), (CH₂N(E¹))_(x)R^(d), (CH₂CH₂N(E₁))_(x)R^(d),halogen, trifluoromethyl, nitro, acyl or cyano,  where R^(d), E¹, E² andE³ are identical or different radicals selected from among hydrogen,alkyl, cycloalkyl and aryl, R^(e) is hydrogen, methyl or ethyl, M⁺is acation, X⁻ is an anion, and x is an integer from 1 to 120, or R¹ and/orR³ together with two adjacent carbon atoms of the benzene ring to whichthey are bound form a fused ring system having 1, 2 or 3 further rings.2. A process as claimed in claim 1, wherein, in the formula I, y¹ and y²are each, independently of one another, a radical of the formulaP(OR⁷)(OR⁸), OP(OR⁷)R⁸ or OP(OR⁷)(OR⁸), where R⁷ and R⁸ are each,independently of one another, alkyl, cycloalkyl, heterocycloalkyl, arylor hetaryl which may bear one, two or three substituents selected fromamong alkyl, cycloalkyl, heterocycloalkyl, aryl, hetaryl, COOR^(f),COO⁻M⁺, SO₃R^(f), SO⁻ ₃M⁺, NE⁴E^(5,) alkylene-NE⁴E⁵, NE⁴E⁵E⁶⁺X⁻,alkylene-NE⁴E⁵E⁶⁺X⁻, OR^(f), SR^(f), (CHR^(g)CH₂O)_(y)R^(f),(CH₂N(E⁴))_(y)R^(f), (CH₂CH₂N(E⁴))_(y)R^(f), halogen, trifluoromethyl,nitro, acyl and cyano,  where R^(f), E⁴, E⁵ and E⁶ are identical ordifferent radicals selected from among hydrogen, alkyl, cycloalkyl oraryl, R^(g) is hydrogen, methyl or ethyl, M⁺is a cation, X⁻ is an anion,and y is an integer from 1 to 120, or R⁷ and R⁸ together with thephosphorus atom and the oxygen atom(s) to which they are bound form a 5-to 8-membered heterocycle to which one, two or three cycloalkyl,heterocycloalkyl, aryl or hetaryl groups may additionally be fused,where the heterocycle and, if present, the fused-on groups may eachbear, independently of one another, one, two, three or four substituentsselected from among alkyl, cycloalkyl, heterocycloalkyl, aryl, hetaryl,COOR^(f), COO⁻M⁺, SO₃R^(f), SO⁻ ₃M⁺, NE⁴E⁵, alkylene-NE⁴E⁵, NE⁴E⁵E⁶⁺X⁻,alkylene-NE⁴E⁵E⁶⁺X⁻, OR^(f), SR^(f), (CHR^(g)CH₂O)_(y)R^(f),(CH₂N(E⁴))_(y)R^(f), (CH₂CH₂N(E⁴))_(y)R^(f), halogen, trifluoromethyl,nitro, acyl and cyano, where R^(f), R^(g), E⁴, E⁵, E⁶, M⁺, X⁻ and y areas defined above.
 3. A process as claimed in either of the precedingclaims, wherein the compound of the formula I is selected from amongcompounds of the formulae I.1 to I.6

where A¹ is O, S or CR⁵R⁶, where R⁵ and R⁶ are each, independently ofone another, hydrogen or C₁-C₄-alkyl, R¹⁷, R¹⁸, R¹⁹, R²⁰, R²¹, R²², R²³and R²⁴ are each, independently of one another,  hydrogen, alkyl,cycloalkyl, heterocycloalkyl, aryl, hetaryl, COOR^(f), COO⁻M⁺, SO₃R^(f),SO⁻ ₃M⁺, NE⁴E⁵, alkylene-NE⁴E⁵, NE⁴E⁵E⁶⁺X⁻, alkylene-NE⁴E⁵E⁶⁺X⁻, OR_(f),SR^(f), (CHR^(g)CH₂O)_(y)R^(f), (CH₂N(E⁴))_(y)R^(f),(CH₂CH₂N(E⁴))_(y)R^(f), halogen, trifluoromethyl, nitro, acyl and cyano, where R^(f), E⁴, E⁵ and E⁶ are identical or different radicals selectedfrom among hydrogen, alkyl, cycloalkyl and aryl, R^(g) is hydrogen,methyl or ethyl, M⁺is a cation, X⁻ is an anion, and y is an integer from1 to
 120. 4. A process as claimed in either of the preceding claims,wherein the metal of transition group VIII is selected from amongcobalt, ruthenium, iridium, rhodium, palladium and platinum.
 5. Aprocess as claimed in either of the preceding claims, wherein thecatalyst further comprises at least one additional ligand selected fromamong halides, amines, carboxylates, acetylacetonate, arylsulfonates andalkylsulfonates, hydride, CO, olefins, dienes, cycloolefins, nitriles,N-containing heterocycles, aromatics and heteroaromatics, ethers, PF₃,phospholes, phosphabenzenes and monodentate, bidentate and polydentatephosphine, phosphinite, phosphonite, phosphoramidite and phosphiteligands.
 6. A process as claimed in either of the preceding claims,wherein the unsaturated compound used for the hydroformylation isselected from among internal linear olefins and olefin mixtures in whichat least one internal linear olefin is present.
 7. A compound of theformula I

where A¹ and A² are each, independently of one another, O, S,SiR^(a)R^(b), NR^(c)or CR⁵R⁶, with the exception of A¹=S and A²=O, whereR^(a), R^(b), R^(c), R⁵ and R⁶ are each, independently of one another,hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl, y¹ andy² are each, independently of one another, radicals containing at leastone phosphorus atom, where in each case at least two substituted orunsubstituted heteroatoms selected from among O, S and NR^(c), whereR^(c) is hydrogen, alkyl, cycloalkyl or aryl, are directly bound to thephosphorus atom, and y¹ and y² are each, independently of one another, aradical of the formula P(OR⁷)(OR⁸), OP(OR⁷)R⁸ or OP(OR⁷)(OR⁸), where R⁷and R⁸ are each, independently of one another, cycloalkyl,heterocycloalkyl, aryl or hetaryl which may bear one, two or threesubstituents selected from among alkyl, cycloalkyl, heterocycloalkyl,aryl, hetaryl, COOR^(f), COO⁻M⁺, SO₃R^(f), SO⁻ ₃M⁺, NE⁴E⁵,alkylene-NE⁴E⁵, NE⁴E⁵E⁶⁺X⁻, alkylene-NE⁴E⁵E⁶⁺X⁻, OR^(f), SR^(f),(CHR^(g)CH₂O)_(y)R^(f), (CH₂N(E⁴))_(y)R^(f), (CH₂CH₂N(E⁴))_(y)R^(f),halogen, trifluoromethyl, nitro, acyl and cyano,  where R^(f), E⁴, E⁵and E⁶ are identical or different radicals selected from among hydrogen,alkyl, cycloalkyl or aryl, R^(g) is hydrogen, methyl or ethyl, M⁺is acation, X⁻ is an anion, and y is an integer from 1 to 120, or R⁷ and R⁸together with the phosphorus atom and the oxygen atom(s) to which theyare bound form a 5- to 8-membered heterocycle to which one, two or threecycloalkyl, heterocycloalkyl, aryl or hetaryl groups may additionally befused, where the heterocycle and, if present, the fused-on groups mayeach bear, independently of one another, one, two, three or foursubstituents selected from among alkyl, cycloalkyl, heterocycloalkyl,aryl, hetaryl, COOR^(f), COO⁻M⁺, SO₃R^(f), SO⁻ ₃M⁺, NE⁴E⁵,alkylene-NE⁴E⁵, NE⁴E⁵E⁶⁺X⁻, alkylene-NE⁴E⁵E⁶⁺X⁻, OR^(f), SR^(f),(CHR^(g)CH₂O)_(y)R^(f), (CH₂N(E⁴))_(y)R^(f), (CH₂CH₂N(E⁴))_(y)R^(f),halogen, trifluoromethyl, nitro, acyl and cyano, where R^(f), R^(g), E⁴,E⁵, E⁶, M⁺, X⁻ and y are as defined above, R¹, R², R³ and R⁴ are each,independently of one another, hydrogen, alkyl, cycloalkyl,heterocycloalkyl, aryl, hetaryl, COOR^(d), COO⁻M⁺, SO₃R^(d), SO⁻ ₃M⁺,NE¹E², NE¹E²E³⁺X⁻, alkylene-NE¹E²E³⁺X⁻, OR^(d), SR^(d),(CHR^(e)CH₂O)_(x)R^(d), (CH₂N(E¹))_(x)R^(d), (CH₂CH₂N(E₁))_(x)R^(d),halogen, trifluoromethyl, nitro, acyl or cyano,  where R^(d), E¹, E² andE³ are identical or different radicals selected from among hydrogen,alkyl, cycloalkyl and aryl, R^(e) is hydrogen, methyl or ethyl, M⁺is acation, X⁻ is an anion, and x is an integer from 1 to 120, or R¹ and/orR² together with two adjacent carbon atoms of the benzene ring to whichthey are bound form a fused ring system having 1, 2 or 3 further rings.8. A catalyst comprising at least one complex of a metal of transitiongroup VIII with at least one ligand selected from among compounds of theformula I

where A¹ and A² are each, independently of one another, O, S,SiR^(a)R^(b), NR^(c) or CR⁵R⁶, with the exception of A¹=S and A²=O,where R^(a), R^(b), R^(c), R⁵ and R⁶ are each, independently of oneanother, hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl,y¹ and y² are each, independently of one another, radicals containing atleast one phosphorus, arsenic or antimony atom, where in each case atleast two substituted or unsubstituted heteroatoms selected from amongO, S and NR^(c), where R^(c) is hydrogen, alkyl, cycloalkyl or aryl, aredirectly bound to the phosphorus, arsenic or antimony atom, and R¹, R²,R³ and R⁴ are each, independently of one another, hydrogen, alkyl,cycloalkyl, heterocycloalkyl, aryl, hetaryl, COOR^(d), COO⁻M⁺, SO₃R^(d),SO⁻ ₃M⁺, NE¹E², NE¹E²E³⁺X⁻, alkylene-NE¹E²E³⁺X⁻, OR^(d), SR^(d),(CHR^(e)CH₂O)_(x)R^(d), (CH₂N(E¹))_(x)R^(d), (CH₂CH₂N(E¹))_(x)R^(d),halogen, trifluoromethyl, nitro, acyl or cyano,  where R^(d), E¹, E² andE³ are identical or different radicals selected from among hydrogen,alkyl, cycloalkyl and aryl, R^(e) is hydrogen, methyl or ethyl, M⁺is acation, X⁻ is an anion, and x is an integer from 1 to 120, or R¹ and/orR² together with two adjacent carbon atoms of the benzene ring to whichthey are bound form a fused ring system having 1, 2 or 3 further rings.